Maternal and newborn care are the leading reasons for hospital admissions in the U.S. Understanding patterns of care during these hospital stays can provide important insights for strategies to reduce health care costs. Moreover, despite the large overall cost for childbirth and increasing use of obstetric interventions, the U.S. ranks poorly in a variety of maternal and perinatal outcome measures relative to other industrialized countries. Experts in obstetrics have called for improved cost to quality ratio in the delivery of maternity care services. Recent evidence on large variation in intrapartum intervention rates across U.S. hospitals and lack of benefit of excessive intervention rates in improving maternal and perinatal outcomes highlight the need to rigorously examine hospital differences in value of intrapartum care. Therefore, the objective of this study is to examine hospital variation in cost and outcomes of care for childbirth-related hospitalizations and to identify hospital attributes associated with high-value care. We hypothesize that cost and outcomes of childbirth hospitalizations differ substantially across hospitals after adjustment for patient case-mix and that hospital cost is not associated with patient outcomes. We further hypothesize that hospitals vary in their pattern of combined financial and clinical outcomes and that differences in hospital organization, delivery, and financing of intrapartum care are associated with distinct cost-outcome patterns. California has the largest number of births among all U.S. states, accounting for 12.7% of the country's total deliveries. With a diverse and large number of hospitals and a unique data system that links maternal and newborn hospital discharge records with birth certificates; California provides an ideal setting for studying hospital variation in intrapartum care. We will therefore test our hypotheses using data from 2007-2015 childbirth-related hospitalizations in California via the following specific aims: 1) To determine variation in risk-standardized cost and maternal and perinatal outcomes across hospitals; 2) To examine the relationship between hospital risk-standardized cost and risk- standardized maternal and perinatal outcomes; 3) To characterize hospital organization, delivery and financing of intrapartum care via a statewide survey; and 4) To classify hospital value of care based on their combined longitudinal pattern of cost and maternal and perinatal outcomes, and to identify hospital and intrapartum care characteristics associated with specific cost-outcome patterns. We will evaluate both maternal and perinatal outcomes when assessing hospital performance, and risk-adjust for patient characteristics using hierarchical generalized linear models. Evaluating hospital cost in conjunction with clinical outcomes will identify patterns in value of care. In addition, use of a novel latent class growth analysis will allow for a more comprehensive classification of hospital performance by revealing temporal trends using longitudinal data. Findings from this study can inform the feasibility of hospital benchmarking in obstetrics, design of value-based payment and health care delivery reforms, and strategies for promoting system-wide value in obstetric care.